#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>

size_t my_strspn(const char* str1, const char* group)
{
	size_t ret = 0;
	while (strchr(group,*str1) != NULL)
	{
		ret++;
		str1++;
	}
	return ret;
}

int main()
{
	char str[] = "abcef3356";
	char group[] = "abcdef";
	size_t len = my_strspn(str, group);
	printf("len = %u", len);
	return 0;
}